Lever-operated microswitches

ABSTRACT

An electric switch, particularly a microswitch, comprises an insulating casing housing the switch movement or mechanism. A rockable actuating member for the mechanism is mounted in an opening in the casing and, inside the latter, operates on a member of the mechanism. Rocking movement of the actuating member actuates the switch mechanism and causes a contact-carrying arm of the mechanism to snap over from one contact position to another. The actuating member is rockably mounted in the opening in the switch casing by means of a cylindrical boss portion of the actuating member engaged in generally part-cylindrical bearing recesses formed respectively in opposite sides of the opening.

United States Patent [72] Inventor Donald Courtney Beer Newick, England[2]] Appl. No. 827,733 [22] Filed May 26, 1969 [45] Patented Sept. 14,1971 [73] Assignee Otehall Limited Sussex, England [32] Priority May 29,1968 [33] Great Britain [31 25819/68 [54] LEVER-OPERATED MICROSWITCHES 8Claims, 5 Drawing Figs.

[52] US. Cl 200/172 B, 200/67 D [51] Int. Cl 110111 3/02 [50] Field ofSearch 200/67,

67.7, 68, 67 D, 67 B, 172 A, 172 B, 164,154

[56] References Cited UNITED STATES PATENTS 2,518,219 8/1950 Brasty200/164 X Primary Examiner-David Smith, .1 r.

Attorney-Holcombe, Wetherill & Brisebois ABSTRACT: An electric switch,particularly a microswitch, comprises an insulating casing housing theswitch movement or mechanism. A rockable actuating member for themechanism is mounted in an opening in the casing and, inside the latter,operates on a member of the mechanism. Rocking movement of the actuatingmember actuates the switch mechanism and causes a contact-carrying armof the mechanism to snap over from one contact position to another. Theactuating member is rockably mounted in the opening in the switch casingby means of a cylindrical boss portion of the actuating member engagedin generally part-cylindrical bearing recesses formed respectively inopposite sides of the openmg.

LEVER-OPERATED MICROSWITCHES The present invention relates to electricswitches, more particularly microswitches, of the type which havehitherto been operated via a plunger or button. The plunger or button ismounted in an opening in the switch casing which houses the switchmovement or mechanism and inside this casing operates on a member of themovement. Depression of the plunger actuates the switch movement andthereby moves a contact-carrying member of the movement from oneposition to another.

The present invention has for an object to provide an arrangement ofswitch of the above type in which the plunger may be replaced by arockable actuating member, such as a lever member or dolly, which mayoperate on the member or portion of the movement which is normallyoperated by the depression of the plunger. To this end, the said openingin the switch casing has two bearing recesses formed respectively inopposite sides of the opening for pivotally mounting a boss portion of arockable actuating member. This enables the same opening in the switchcasing, and thus the same casing, to be used for either a plunger orrockable actuating member. In the latter case, the boss portion of theactuating member is pivotally mounted in the beating recesses in theopening and the actuating member includes a cam portion projecting intothe switch casing and bearing on said member or portion of the switchmovement, whereby pivoting of the actuating member in one directionactuates the movement in order to move the contact carrying member fromits one position to the other, and an externally projecting portion orpart by which the actuating member may be rocked. Conveniently, the bossportion of the actuating member is generally cylindrical and the bearingrecesses formed in opposite sides of the opening are of substantiallypart-cylindrical shape.

The externally projecting part of the actuating member may comprise alever. The latter may be a separate part secured to the boss portion ormay, alternatively, be integral therewith. Conveniently, the lever isformed from a metal strip whilst the boss and cam portions of the memberare moulded from synthetic plastics material, such as nylon, and aremoulded onto the metal strip. The lever may be directed to the right orleft with respect to the pivoting axis of the boss portion.Alternatively the lever may be moulded of plastics material and may bemoulded integrally with the boss and cam portions.

The invention is used with particular advantage in lever operatedswitches. Hitherto, when it was required to produce a lever-operatedswitch of the type above referred to, a lever was arranged to bear onthe plunger and it was necessary to provide additional means on theswitch, remote from the plunger, for forming a fulcrum for one end ofthe lever and about which the lever could be pivoted so as to depressthe plunger and actuate the switch movement. With the present invention,it is unnecessary to provide a separate fulcrum for the lever. Thefulcrum is the rocking axis of the actuating member of which the leverforms a part and which is substituted for the plunger.

In one embodiment of the invention, the switch movement comprises aspring-loaded, overcenter mechanism arranged to cause the contactcarrying member to snap over from its one or rest position to the otheror actuated position in response to actuation of the mechanism by theactuating member. The mechanism automatically returns thecontact-carrying member to said one position, under the action of itsspring, upon release of the actuating member.

In prior lever-operated switches where a separate fulcrum is providedfor the lever which bears on the plunger, the lever has a certain amountof side play, which is not ideal. With the present invention, the factthat the lever forms part of or is integral with the boss portion of theactuating member and the spring return action of the overcenter switchmechanism presses the boss portion into its bearing recesses tends toeliminate side play.

By a suitable arrangement of the cam of the actuating member, thespring-loaded, over center mechanism may be locked in the actuatedposition and prevent automatic restoring of the contact member to itsrest position upon release of the actuating member. When using such alocking arrangement, the equipment to which the switch is fitted mustincorporate its own on and off tripping mechanism for positivelyreturning the actuating member to its initial position so as to effectrelease of the overcenter mechanism and return of the contact-carryingmember to its rest position.

In order that the present invention may be more readily understood,reference will now be made to the accompanying drawings, in which;

FIG. 1 is a side view of a lever-operated microswitch constructed inaccordance with the invention, the switch being illustrated with thefacing sidewall of its casing removed so as to show the switchmechanism,

FIG. 2 is a fragmentary view of the switch of FIG. 1 illustrating theuse ofa plunger in place of the lever,

FIGS. 3 and 4 are fragmentary views of a switch similar to thatillustrated in FIG. 1 with the cam portion of the lever-type actuatingmember designed to effect locking of the overcenter mechanism of theswitch in its actuated position, and

FIG. 5 is a fragmentary view of a switch similar to that shown in FIG. 1and illustrating the use of a dolly as the actuating member.

Referring to FIG. 1 of the drawings, the snap action microswitchincludes a moulded insulating casing 1 provided with two fixingapertures 2. It is a two-way switch in which a terminal 3 may beconnected through a hinged contact-carrying arm or member 4 to one orother of the terminals 5 and 6. The contact-carrying arm is hinged atone end to a support member 7 which is an integral extension of theterminal 3 and has its end remote from the terminal 3 supported in slot8 formed in the top wall of the casing l. The contact-carrying arm is abifurcated member and the free ends of the fork arms 14 form a hingeconnection with an inclined part of the support member. The supportmember has a slot 15 extending along a major portion of its length andthe free ends of the fork arms are formed with projecting portions 16which rest against transverse shoulders (not shown) at opposite sides ofthe slot 15 whilst the transverse shoulders 17 adjacent the projectingportions 16 rest on the support member.

The end of the contact-carrying arm 4 remote from its hinge is providedwith contacts 9 for engaging fixed contacts 10 and 11 associatedrespectively with the terminals 5 and 6.

The contact-carrying arm is moved about its hinge selectively to engagethe contacts 9 with the contacts 10 and 11 by the over center action ofa rocker member 12 hingedly connected at one end to the arm 4 and, atits opposite end, to a leaf spring or strip spring 13 which is heldunder compression between the end of the rocker member and the supportmember 7.

Through the rocker member, the spring resiliently urges the movingcontact-carrying arm against its hinge connection with the supportmember 7.

The rocker member 12 extends through the slot 15 and is hinged to thearm by a tongue portion 19 bearing against one end of a rectangularopening 20 in the arm 4 and transverse shoulders 22 at opposite sides ofthe tongue portion resting on the arm on opposite sides of the aperturetherein. At its opposite end the rocker member is hinged to the leafspring 13. At this end, the member 12 is bifurcated and each fork arm 23has a laterally projecting portion 24 forming a transverse shoulder 25.The free ends of the arms 23 are bent downwardly and the shoulder 25engage respectively behind a pair of spaced lugs 26 which project fromthe adjacent end of the spring 13. The arms 23 also rests on alignedtransverse edges of the adjacent end of the spring between the lugs 26.

The other end of the spring 13 is hinged to the support member 7. Atongue 27 at this end of the spring projects into the slot 15 andengages against the transverse end wall 28 of the slot. Moreover,transverse shoulders on opposite .sides of the tongue portion restrespectively against the support member.

The switch is is operated by an actuating member 29 pivotally mounted inthe wall of the casing 1 so as to be rockable about an axissubstantially parallel to the hinge axes of the various members of theovercenter mechanism. The actuating member is pivotally mounted in arectangular opening 30 in the casing by having a cylindrical bossportion 31 engaged in a pair of opposed part-cylindrical bearingrecesses 32 moulded in opposite sides of the opening. Projecting intothe interior of the casing is a cam portion 33 of the actuating memberwhich has a slightly curved cam surface 34 engaging a tongue portion 35projecting from the adjacent end of the spring between the lugs 26. Thetongue portion 35 is bent so that the cam surface 34 engages the uppersurface of the tongue portion.

Projecting externally of the switch casing is a lever 36 which formspart of the actuating member, the lever being rigidly secured to theboss portion 31. The lever is formed from metal strip, for example,stainless steel strip, whilst the boss and cam portions of the actuatingmember are mounded from synthetic plastics material, such as nylon. Theboss and cam portions are moulded onto' the downwardly projecting endportion 37 of the lever. This downwardly projecting end portion hasnotches 38 cut in opposite sides thereof and, where the end portion isembedded in the material of the boss portion, the material of the bossportion fills the notches during the moulding operation so that thelever is securedly fixed to the boss portion.

The contact-carrying arm 4 and the rocker member 12 are normally biassedby snaps over leaf spring 13 in the rest position shown in the drawingin which the contacts 9 and are in engagement. In this rest position,the end face 39 of the cam portion 33 of the actuating member abuts theinside of the casing 1, as shown, to limit movement of the overcentermechanism. When the lever 36 is depressed, the actuating member 29pivots in an anticlockwise direction about its rocking axis and the camsurface 34 acts on the tongue portion 35 to depress the left-hand endsof the spring and rocker member so that the line joining the hingeconnections of the rocker member with the contact carrying arm 4 and thespring moves overcenter with respect to the hinge axis of the arm 4 onthe support member 7, whereupon the arm 4 snaps over I from its upper orrest position shown in the drawing into its lower or actuated positionin which the contacts 9 and 11 are in engagement. Release of the leverarm permits the overcenter mechanism and actuating member to return totheir initial positions under the action of the spring 13 and thecontact-carrying arm snaps back into the rest position.

FIG. 2 illustrates the replacement of the rockable actuating member 29comprising the boss, cam portion and lever by a conventional plunger 40.The plunger is slidably mounted in the rectangular opening 30 in theswitch casing 1. The plunger is of rectangular cross section andprojects externally of the switch casing. its lower inner end bears onthe apex of the bend in the adjacent end of the rocker member and isformed with outwardly projecting flanges 41. Alternatively, the lowerend of the plunger may bear on the spring 13. The flanges 41 serve asstops which engage the inside of the casing, as shown, to limit upwardmovement of the plunger under the spring return action of the overcentermechanism. As will be apparent, depression of the plunger actuates theovercenter "mechanism to snap over the arm 4 into the position in which"it'sjcontacts "9 and 11 engage and, upon release of the plunger, themechanism returns the arm to its position.

so that its cam surface 44 curves or nearly curves back on itself. Inthe rest position of the switch, the cam surface bears on the tongueportion 35 of the spring 13, as shown in FIG. 3, and

the overcenter mechanism in the same position as that illustrated inFIG. 1. Upon depression of the lever 45, the cam surface 44 moves in ananticlockwise direction and depresses the tongue portion of the springso that the mechanism is actuated. In doing so, the actuating membermoves to the position shown in FIG. 4. in this position, the action ofthe spring [3 on the cam surface tends to rotate the actuating member inan anticlockwise direction and not to return the actuating member in aclockwise direction to its initial position. Further anticlockwisemovement of the actuating member is, however, prevented by the camportion 42 abutting the inside of the switch casing and thus the camportion and spring interengage to lock the overcenter mechanism in itsactuated condition. In order to release the overcenter mechanism, it isnecessary positively to raise the lever 45 and pivot the actuatingmember in a clockwise direction. When the elbow 46 of the cam surfacemoves over the apex of the tongue portion 35, the lock is released andthe contact arm is snapped back into its rest position under thespring-return action of the overcenter mechanism.

Referring to H6. 5, in this embodiment the actuating member is in theform of a dolly 48. As in the previous embodiments, it includes acylindrical boss portion 49 pivotally mounted in the opposedpart-cylindrical bearing recesses 32 in the switch casing l. Projectinginwardly from the boss portion is a spigot 50 which has a rounder innerend 51 engaging the tongue portion 35 of the spring 13. Projectingexternally of the switch casing from the boss portion is a dollyoperating portion 52. When the dolly is in the position illustrated, thecontact arm is in its upper position shown in FIG. 1. Movement of thedolly in an anticlockwise direction causes. the spigot 50 to depress thetongue portion 35 of the spring and thereby snap the contact arm intoits lower position. in this position, the spigot is in engagement withthe spring at a position just over the apex of the bend 53 in the tongueportion 35 and the overcenter mechanism is locked with the contact armin its lower position. The spring tends to pivot the dolly in ananticlockwise direction but this is prevented by the spigot engaging theinside of the casing. Movement of the dolly in the opposite directionreleases the overcenter mechanism and permits the latter to snap thecontact arm back into its upper position. The dolly may be a one-piecemoulding of plastics material.

it will be apparent from the above description that the presentinvention readily permits a particular switching mechanism and itscasing to be provided with any one of a variety of different types ofactuating member which is selected according to requirements. Oneopening 30 in the switch casing is all that is necessary for suitablymounting any selected actuating member.

While particular embodiments have been described, it will be understoodthat modification can be made without departing from the scope of theinvention as defined by the appended claims. For example, the lever arm36 may be arranged to project in the opposite direction from that shownin the drawings, in which case, the cam surface 34 will also be inclinedin the opposite direction from that shown in the drawings so that thecam surface bearson the spring 13 between the fork arms 23 of the rocketmember 12. Moreover, the cam surface 34 may be alternatively arranged toact on the rocker member 12 or onadjacent portions of both the spring 13and the rocker member. Any suitable construction of overcenter mechanismmay be used, in place of that specifically illustrated, to controlmovement of the contact-carrying arm. I claim:

1. In a microswitch having a casing and a switch mechanism mountedwithin said casing, said casing having an opening therein forreciprocally receiving a plunger which is capable of projecting intosaid casing to engage said mechanism for actuating same upon depressionof said plunger, the improvement comprising two concave bearing recessesformed respectively in opposite sidewalls of said opening, and arockable actuating member mounted in said opening in place of saidplunger, said actuating member having a boss portion pivotally mountedin said bearing recesses and a cam portion projecting into said casingto engage said mechanism and adapted to actuate said mechanism uponrocking of the actuating member in said recesses.

2. A microswitch as claimed in claim 1, wherein said switch casing isformed from insulating material, and said bearing recesses are formed inthe insulating material defining said sidewalls of the opening asgenerally part-cylindrical bearing recesses, and wherein said rockableactuating member comprises a cylindrical boss portion pivotally mountedin said part-cylindrical bearing recesses, said cam portion projectingfrom said boss portion into said switch casing and bearing on a memberof the switch mechanism, and an externally projecting part by which saidactuating member is rocked to actuate the mechanism.

3. A microswitch as claimed in claim 2, wherein said boss and camportions of said actuating member are integrally moulded from plasticsmaterial and said externally projecting part comprises a lever formedfrom metal strip and moulded into said boss portion.

4. A microswitch as claimed in claim 2, wherein said actuating member isin the form of a dolly and comprises a boss, cam and dolly operatingportion integrally moulded from plastics material.

5. A microswitch as claimed in claim 2, wherein said switch mechanismcomprises a spring-loaded, overcenter mechanism arranged to cause amovable contact carrying member to snap over from a rear position to anactuated position in response to actuation of said mechanism by saidactuating member, said mechanism automatically returning said contactcarrying member to its rest position, under the action of the spring,upon release of said actuating member.

6. A microswitch as claimed in claim 5, wherein said switch mechanismcomprises a movable contact carrying arm arranged to snap over from arest position to an actuated position about an axis substantiallyparallel to the axis of said boss portion upon actuation of thespring-loaded, overcenter mechanism, said mechanism comprising a rockermember connected to said contact arm and extending transversely to saidarm axis to project on the opposite side thereof to that on which saidrocker member is connected to said arm, and a compression springconnected to said rocker member at a position on said opposite side ofsaid arm axis and arranged to act on said rocker member so as to urgethe connection between said rocker member and said arm towards said armaxis, the connections of said rocker member to said arm and said springbeing so disposed that a line joining said connections moves overcenterwith respect to said arm axis upon actuation of said mechanism in orderto cause said arm to snap over from said rest position to said actuatedposition, and wherein said opening mounting said rockable actuatingmember is disposed adjacent said connection between said spring androcker member and said cam portion engages an adjacent part of one ofthese members.

7. A microswitch as claimed in claim 6, wherein said cam portion, insaid rest position of said contact arm, engages said switch casing toserve as a stop limiting movement of said mechanism.

8. A microswitch as claimed in claim 6, wherein said cam portion isadapted to lock said spring-loaded mechanism in said actuated positionof said contact arm and prevent automatic restoring of said contact armto its rest position upon release of said actuating member.

1. In a microswitch having a casing and a switch mechanism mountedwithin said casing, said casing having an opening therein forreciprocally receiving a plunger which is capable of projecting intosaid casing to engage said mechanism for actuating same upon depressionof said plunger, the improvement comprising two concave bearing recessesformed respectively in opposite sidewalls of said opening, and arockable actuating member mounted in said opening in place of saidplunger, said actuating member having a boss portion pivotally mountedin said bearing recesses and a cam portion projecting into said casingto engage said mechanism and adapted to actuate said mechanism uponrocking of the actuating member in said recesses.
 2. A microswitch asclaimed in claim 1, wherein said switch casing is formed from insulatingmaterial, and said bearing recesses are formed in the insulatingmaterial defining said sidewalls of the opening as generallypart-cylindrical bearing recesses, and wherein said rockable actuatingmember comprises a cylindrical boss portion pivotally mounted in saidpart-cylindrical bearing recesses, said cam portion projecting from saidboss portion into said switch casing and bearing on a member of theswitch mechanism, and an externally projecting part by which saidactuating member is rocked to actuate the mechanism.
 3. A microswitch asclaimed in claim 2, wherein said boss and cam portions of said actuatingmember are integrally moulded from plastics material and said externallyprojecting part comprises a lever formed from metal strip and mouldedinto said boss portion.
 4. A microswitch as claimed in claim 2, whereinsaid actuating member is in the form of a dolly and comprises a boss,cam and dolly operating portion integrally moulded from plasticsmaterial.
 5. A microswitch as claimed in claim 2, wherein said switchmechanism comprises a spring-loaded, overcenter mechanism arranged tocause a movable contact carrying member to snap over from a rearposition to an actuated position in response to actuation of saidmechanism by said actuating member, said mechanism automaticallyreturning said contact carrying member to its rest position, under theaction of the spring, upon release of said actuating member.
 6. Amicroswitch as claimed in claim 5, wherein said switch mechanismcomprises a movable contact carrying arm arranged to snap over from arest position to an actuated positiOn about an axis substantiallyparallel to the axis of said boss portion upon actuation of thespring-loaded, overcenter mechanism, said mechanism comprising a rockermember connected to said contact arm and extending transversely to saidarm axis to project on the opposite side thereof to that on which saidrocker member is connected to said arm, and a compression springconnected to said rocker member at a position on said opposite side ofsaid arm axis and arranged to act on said rocker member so as to urgethe connection between said rocker member and said arm towards said armaxis, the connections of said rocker member to said arm and said springbeing so disposed that a line joining said connections moves overcenterwith respect to said arm axis upon actuation of said mechanism in orderto cause said arm to snap over from said rest position to said actuatedposition, and wherein said opening mounting said rockable actuatingmember is disposed adjacent said connection between said spring androcker member and said cam portion engages an adjacent part of one ofthese members.
 7. A microswitch as claimed in claim 6, wherein said camportion, in said rest position of said contact arm, engages said switchcasing to serve as a stop limiting movement of said mechanism.
 8. Amicroswitch as claimed in claim 6, wherein said cam portion is adaptedto lock said spring-loaded mechanism in said actuated position of saidcontact arm and prevent automatic restoring of said contact arm to itsrest position upon release of said actuating member.